[Translate] Factor out access to Accept-Languages

components/translate/core/browser/translate_prefs.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_PREFS_H_
 #define COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_PREFS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 114 matching lines @@
   // Update the last time on closing the Translate UI without translation.
   void UpdateLastDeniedTime(const std::string& language);
 
   // Returns true if translation is denied too often.
   bool IsTooOftenDenied(const std::string& language) const;
 
   // Resets the prefs of denial state. Only used internally for diagnostics.
   void ResetDenialState();
 
   // Gets the language list of the language settings.
-  void GetLanguageList(std::vector<std::string>* languages);
+  void GetLanguageList(std::vector<std::string>* languages) const;
 
   // Updates the language list of the language settings.
   void UpdateLanguageList(const std::vector<std::string>& languages);
 
   bool CanTranslateLanguage(TranslateAcceptLanguages* accept_languages,
                             const std::string& language);
   bool ShouldAutoTranslate(const std::string& original_language,
                            std::string* target_language);
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
   static void MigrateUserPrefs(PrefService* user_prefs,
@@ skipping 39 matching lines @@
   base::DictionaryValue* GetTranslationAcceptedCountDictionary() const;
 
   PrefService* prefs_;  // Weak.
 
   DISALLOW_COPY_AND_ASSIGN(TranslatePrefs);
 };
 
 }  // namespace translate
 
 #endif  // COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_PREFS_H_